The Vasculitis Clinical Research Consortium (VCRC) was established in 2003 and in 5 years of rapid growth and productivity has become the major clinical research infrastructure in North America dedicated to the study of vasculitis. The VCRC is a founding member and leading force of the NIH Rare Diseases Clinical Research Network (RDCRN). By conducting a series of longitudinal cohort studies, biomarker discovery projects, multicenter clinical trials, and outcome measure development projects, the Consortium is addressing serious unmet medical and scientific needs for this group of complex rare diseases. The VCRC currently has over 500 patients in clinical research on the following 6 types of vasculitis: giant cell arteritis, Takayasu's arteritis, polyarteritis nodosa, Wegener's granulomatosis, microscopic polyangiitis, and Churg Straus Syndrome. Each of these diseases are consider "orphan" diseases. Additionally, partnership with patient advocacy groups has been a critical component to the success of the VCRC. The VCRC electronic resources are important for patients worldwide. The VCRC Fellowship Program has successfully trained new clinical investigators, each of whom remains engaged in academic research in vasculitis. This proposal outlines a total of 13 separate clinical protocols with 10 associated studies of biomarkers VCRC investigators have successfully obtained ancillary funding to allow for expansion of the Consortium's work. Sources of these funds include the NIH, the FDA, private foundation and the biopharmaceutical industry. This application seeks refunding of the VCRC to both support the critical administrative, laboratory, biostatistical cores and allow completion of ongoing projects, launch of exciting new scientific initiatives training of new investigators in clinical research in vasculitis, and expansio n of the VCRC website.